At this point the 328i AT and 335i AT have the same MPG rating city and highway. For day to day driving I don't see how there would be much difference in MPG as both cars use the same trans with the same gearing, and will require the same power output.

The actual MPG difference will be seen when the 335i is driven harder as it puts out more power.
But for daily driving there isn't going to be that much of an MPG difference created by the 145lb difference between the versions.
Yes, there will be some difference in MPG especially with drivers who are more aggressive in either version.
However it seems much comment is made about how the 328i has such better MPG over the 335i. But let's see the actual difference. How muc is it really? It may be 1 to 3mpg. Is that enough so that one chooses the 328i over the 335i, if one only used MPG as the deciding factor?
It's not like the difference is 5mpg or higher.

I'm averaging between 25.5 to 27mpg in my 335i Msport w/sport AT on sticky summer high performance tires, and that includes daily commuting with spirited driving in the mix.
My 135i 6MT only managed between 21.5 to 22mpg and it was a lighter coupe, driven in the same manner on the same routes.
With the 8spd AT it's actually quite impressive how good of an MPG the 335i does get